micro: Don't forward nil events into the sub event handler (#2992)

cmd/micro/micro.go

@@ -449,6 +449,10 @@ func DoEvent() {
 		os.Exit(0)
 	}
 
+	if event == nil {
+		return
+	}
+
 	if e, ok := event.(*tcell.EventError); ok {
 		log.Println("tcell event error: ", e.Error())
 
@@ -469,12 +473,10 @@ func DoEvent() {
 	}
 
 	ulua.Lock.Lock()
-	// if event != nil {
 	if action.InfoBar.HasPrompt {
 		action.InfoBar.HandleEvent(event)
 	} else {
 		action.Tabs.HandleEvent(event)
 	}
-	// }
 	ulua.Lock.Unlock()
 }